Method for depositing silicon nanocrystals in hollow fibers

Abstract

A method for depositing a layer of silicon nanocrystals upon the inside surface of hollow fibers is disclosed. In particular, the method includes inserting a hollow glass fiber into a solution of hydrogen silsesquioxane, removing the solvent and heating the hollow glass fiber to a temperature suitable to form silicon nanocrystals, and subsequently cooling the hollow glass fiber.

The invention claimed is: 
     
       1. A method for depositing a layer of silicon nanocrystals on an inner surface of a hollow fiber and obtaining whispering gallery mode resonator, the method comprising:
 a) inserting a tip of the hollow fiber into a solution of hydrogen silsesquloxane (HSQ) in a suitable solvent at an angle of about 70° to about 90° between the fiber and the solution, wherein an inner surface of the fiber is coated with the HSQ solution by capillary action; 
 b) heating the coated hollow fiber in a reducing atmosphere under conditions to remove the solvent; 
 c) heating the hollow fiber in a reducing atmosphere to a temperature suitable to form silicon nanocrystals; and 
 d) cooling the hollow fiber to obtain the whispering gallery mode resonator. 
 
     
     
       2. The method according to  claim 1 , wherein the hollow fiber has an inner diameter of about 1 μm to about 250 μm. 
     
     
       3. The method according to  claim 2 , wherein the hollow fiber has an inner diameter of 25 μm to about 50 μm. 
     
     
       4. The method according to  claim 1 , wherein the hollow fiber is a hollow glass fiber. 
     
     
       5. The method according to  claim 4 , wherein the hollow fiber is a hollow fused silica fiber. 
     
     
       6. The method according to  claim 1 , wherein the fiber is cleaned and dried prior to insertion into the HSQ solution. 
     
     
       7. The method according to  claim 1 , wherein the solvent is methyl isobutyl ketone. 
     
     
       8. The method according to  claim 1 , wherein the reducing atmosphere comprises hydrogen gas. 
     
     
       9. The method according to  claim 8 , wherein the hydrogen gas is present at a concentration of about 1% to about 10% by weight. 
     
     
       10. The method according to  claim 1 , wherein the conditions in b) comprise heating to a suitable temperature of about 250° C. to about 350° C. 
     
     
       11. The method according to  claim 10 , wherein the temperature is increased to the suitable temperature at a rate of about 5° C./min. 
     
     
       12. The method according to  claim 1 , wherein the conditions in b) comprise heating at the suitable temperature for about 1 hour to about 3 hours. 
     
     
       13. The method according to  claim 1 , wherein the suitable temperature in c) is from about 900° C. to about 1300° C. 
     
     
       14. The method according to  claim 13 , wherein the suitable temperature in c) is about 1100° C. 
     
     
       15. The method according to  claim 13 , wherein the temperature is increased to the suitable temperature in c) at a rate of about 18° C./min. 
     
     
       16. The method according to  claim 1 , wherein the hollow fiber is heated at the suitable temperature in c) for about 0.5 hours to about 2 hours. 
     
     
       17. The method according to  claim 1 , wherein the hollow glass fiber is cooled in d) to room temperature. 
     
     
       18. The method according to  claim 17 , wherein the hollow glass fiber is cooled in d) at a rate of about 2° C./min. 
     
     
       19. The method of  claim 1 , wherein the whispering gallery mode resonator is a luminescent whispering gallery mode resonator.